The improved electrolyte system for lithium battery

Lithium-ion batteries (LIBs) are one of the most widely used portable power sources, especially for the cellar phones, camcorders and portable computers. The development of the next generation of lithium ion batteries for Electric Vehicle (EV), Hybrid Electric Vehicle (HEV), or Plug-in Hybrid Electric Vehicle (PHEV) requires the development of improved electrolytes. To date, the commercially available LIBs have a normal discharge voltage\u27 around 3.7V at which the oxidation of electrolytes on the surface of cathodes is typically not considered a significant problem. However, recent interest in high voltage cathode materials (\u3e4.5 V vs Li/Li+) has raised concerns about the LiPF6/carbonate based electrolyte stability to oxidation. Furthermore, the flammability of organic electrolyte also limit LIBs\u27 application in the EV market and other manned space vehicles. A detailed investigation of the 5V cathode surface with/without additives, including 2,5-dihydrofuran (2,5-DHF) and γ-buyrolactone (GBL), Lithium bis (oxalato) borate (LiBOB) and Lithium difluoro (oxalato) borate (LiODFB) and related additives was conducted. Furthermore, surface characterization of electrodes with/without phosphorus base flame-retardants was also investigated. The research tools used in this dissertation include CV, EIS, NMR, GC-Mass, XPS, FTIR-ATR, SEM-EDS and TGA